Jet stack brazing in a diffusion furnace

Abstract

A method for batch brazing jet stacks in a diffusion furnace. The method may include inserting fusible parts into slots of quartz boats and transporting the quartz boats into an interior of a reaction chamber of a diffusion furnace. An operator may seal the interior of the reaction chamber and an atmosphere of the interior of the reaction chamber may be adjusted according to a brazing recipe. A preheated furnace heating element may be moved toward the reaction chamber to increase a temperature and the fusible parts may be brazed according to the brazing recipe. The furnace heating element may then be moved away from the reaction chamber, the chamber unsealed, and the brazed parts removed.

What is claimed is: 
     
       1. A method for batch brazing in a diffusion furnace, comprising:
 inserting a plurality of fusible parts into a plurality of slots of at least one quartz boat; 
 transporting the at least one quartz boat, including the fusible parts, into an interior of a reaction chamber of the diffusion furnace; 
 disposing an insulation band near a load zone of the diffusion furnace; 
 includes disposing the insulation band between an end cap of the reaction chamber and an inner portion of the load zone of the reaction chamber; wherein disposing the insulation band near the load zone of the diffusion furnace includes the insulation band exerting outward radial pressure to hold the insulation band in place without causing damage to the reaction chamber or the end cap; 
 sealing the interior of the reaction chamber; 
 adjusting an atmosphere of the interior of the reaction chamber according to a recipe; 
 moving a preheated furnace heating element from a location spaced apart from the reaction chamber to a location in substantial proximity with the reaction chamber to increase a temperature of the atmosphere of the interior of the reaction chamber above a predefined brazing temperature for a predefined brazing time period according to the recipe. 
 
     
     
       2. The method of  claim 1 , further comprising:
 brazing the fusible parts; 
 moving the preheated furnace heating element from the location in substantial proximity with the reaction chamber to the location spaced apart from the reaction chamber to decrease the temperature of the atmosphere of the interior of the reaction chamber until the atmosphere cools to about room temperature. 
 
     
     
       3. The method of  claim 2 , further comprising:
 unsealing the interior of the reaction chamber; and 
 removing the at least one quartz boat, including the fusible parts, from the interior of the reaction chamber, 
 wherein the fusible parts comprise jet stacks. 
 
     
     
       4. The method of  claim 3 , wherein sealing and unsealing are performed using an end cap, and wherein the reaction chamber is a quartz tube. 
     
     
       5. The method of  claim 3 , further comprising:
 identifying brazed jet stacks removed from the interior of the reaction chamber that were located near a load zone of the reaction chamber; 
 inspecting for uniform gold flow around aperture holes of the brazed jet stacks that were located near the load zone; and 
 inferring that brazed jet stacks removed from the interior of the reaction chamber that were not located near the load zone have the uniform gold flow around the aperture holes responsive to the inspection. 
 
     
     
       6. The method of  claim 2 , wherein the fusible parts include individual plates, and wherein brazing further comprises alloying the individual plates into a plurality of hermetically sealed brazed jet stacks. 
     
     
       7. The method of  claim 6 , wherein each of the individual plates comprises a stainless steel plate having a plating of gold, and wherein alloying the individual plates includes using the moveable furnace heating element to cause the gold to flow so as to fuse the individual plates together around aperture holes. 
     
     
       8. The method of  claim 1 , wherein adjusting the atmosphere of the interior of the reaction chamber according to the recipe includes:
 purging substantially all oxygen (O 2 ) from the interior of the reaction chamber using a flow of nitrogen (N 2 ) into the reaction chamber; 
 measuring the oxygen (O 2 ) concentration in the interior of the reaction chamber during the purge; 
 preventing the preheated furnace heating element from moving to the location in substantial proximity with the reaction chamber until the oxygen (O 2 ) concentration is below a predefined value; and 
 stopping the flow of nitrogen (N 2 ) and starting a flow of hydrogen (H 2 ) when the preheated furnace heating element begins moving to the location in substantial proximity with the reaction chamber so as to create a reducing atmosphere. 
 
     
     
       9. The method of  claim 8 , wherein:
 the predefined value of the oxygen (O 2 ) concentration is about 50 parts per million (ppm); 
 the predefined brazing temperature is about 1100 degrees Celsius; and 
 the predefined brazing time is about four minutes. 
 
     
     
       10. The method of  claim 1 , further comprising:
 maintaining, using the insulation band, the brazing temperature around the load zone during the predefined brazing time period according to the recipe. 
 
     
     
       11. The method of  claim 1 , wherein the recipe comprises segments, and wherein each segment comprises segment titles and an alarm associated with each title, and wherein the method further comprises:
 triggering at least one alarm based on feedback information; 
 displaying one of the segment titles responsive to the associated alarm; and 
 skipping out of at least one segment of the recipe responsive to the at least one alarm. 
 
     
     
       12. The method of  claim 1 , wherein transporting the at least one quartz boat into the interior of the reaction chamber includes placing the at least one quartz boat onto a quartz cradle and loading the quartz cradle into the reaction chamber of the diffusion furnace. 
     
     
       13. The method of  claim 1 , wherein the brazing of the fusible parts is performed as a batch without the use of a continuous belt. 
     
     
       14. The method of  claim 1 , wherein the insulation band comprises high temperature rope. 
     
     
       15. The method of  claim 1 , wherein disposing the insulation band near the load zone of the diffusion furnace includes holding the insulation band in place without the use of adhesive. 
     
     
       16. A method for determining a brazing recipe, comprising:
 attaching first, second, and third temperature sensors to first, second, and third jet stacks, respectively; 
 inserting the first, second, and third jet stacks into a reaction chamber of a diffusion furnace using a paddle; 
 disposing an insulation band near a load zone of the diffusion furnace includes disposing the insulation band between an end cap of the reaction chamber and an inner portion of the load zone of the reaction chamber; 
 wherein disposing the insulation band near the load zone of the diffusion furnace includes the insulation band exerting outward radial pressure to hold the insulation band in place without causing damage to the reaction chamber or the end cap; 
 comparing a temperature reading between the first, second, and third temperature sensors attached to the first, second, and third jet stacks, respectively, with at least one temperature sensor attached to the paddle; 
 tuning the brazing recipe responsive to the comparison; and 
 removing the first, second, and third temperature sensors from the first, second, and third jet stacks, respectively. 
 
     
     
       17. The method of  claim 16 , wherein:
 the temperature sensors comprise thermocouples; 
 the first jet stack is located near a load zone of the reaction chamber; 
 the second jet stack is located near an end of the reaction chamber opposite the load zone; and 
 the third jet stack is located near the middle of the reaction chamber between the load zone and the end opposite the load zone. 
 
     
     
       18. The method of  claim 16 , wherein comparing the temperature further includes comparing the temperature reading between the first, second, and third temperature sensors attached to the first, second, and third jet stacks, respectively, with a plurality of temperature sensors distributed among several locations at a bottom portion of the paddle.